The invention relates to a belt reinforcing fabric, but more particularly, the invention relates to a reinforcing fabric particularly useful in reinforcing belt teeth and a toothed power transmission belt made with such fabric.
Toothed power transmission belts have a polymeric body such as of a rubber, thermoplastic, or urethane, with a plurality of teeth formed along at least one side of such belts. A tensile member is typically embedded in a body as a load carrying member. It is preferred to have the belt teeth reinforced with a fibrous material to enhance their shear strength and wear-resistance, or to alter their coefficient of friction for engagement with a toothed pulley. Wear-resistant fabrics for belts are of a woven type such as a canvas, a crimped stretchable nylon, and a leno-weave, etc., and may be of a knit fabric such as a 1.times.1 rib knit. Such fabrics are disposed in the belt at a peripheral surface that includes the belt teeth and may be in the form of single layer fabrics, multiple layers of woven fabrics, bonded layers of fabrics, and fabrics with an outer layering of an impervious thermoplastic film.
Other fabric reinforcements for reinforcing belt teeth may be of the non-woven type and include a web of discontinuous fibers or a web of fibers that are bonded together by thermal or chemical bonding or needle-punching in known fashion to form a non-woven fabric. Such non-woven belt fabrics are typically embedded in a belt body and may be used to help locate a belt's pitch line diameter (PLD) for a spirally wound tensile cord at lands located between spaced belt teeth. The fabrics are sometimes in an expanded form near a middle portion of the belt tooth where they act as a tooth reinforcement. With some non-woven fabrics, it is difficult to control a requisite thickness for maintaining an acceptable PLD. Some non-woven fabrics are difficult to handle and position at a desired location within belt teeth because of processing limitations of belt manufacture. Examples of fabric reinforcements for belts and belts reinforced therewith are disclosed in the following patents:
U.S. Pat. No. 3,964,328 (Redmond) discloses a fabric in the preferable form of a stretchable nylon with a thermoplastic layer such as polyethylene bonded to an exterior surface thereof. The fabric is disposed at a peripheral surface of a belt including belt teeth as a wear-resistant fabric and friction modifying reinforcement.
U.S. Pat. No. 4,099,422 (Cicognai et al.) discloses a rubberized fabric. Two layers of the fabric are disposed along a peripheral surface of a belt including belt teeth for wear-resistance and rigidifying the belt teeth.
U.S. Pat. No. 4,235,119 (Wetzel) discloses a fabric disposed along a peripheral surface of a belt including belt teeth as a wear-resistant fabric. Discontinuous fibers are compounded into a rubber elastomer of a belt body and are located adjacent the fabric and a tensile member for rigidifying the belt teeth.
U.S. Pat. No. 4,605,389 (Westhoff) discloses a fabric of the type as used in Redmond '328. The fabric is disposed along a peripheral surface of a belt including spaced belt teeth where the belt teeth are configured flank surfaces having a tractrix curve shape.
U.S. Pat. No. 4,895,555 (Watanabe et al.) discloses a web of non-woven fabric. The non-woven fabric is used as a reinforcement with a cast urethane belt body and is compressed under a tensile member in a land area of a belt and is diffused in belt teeth as a reinforcing fiber for improving the shear strength of the teeth.
U.S. Pat. No. 5,362,281 (Dutton) discloses a double woven fabric with two sets of warp yarns and two sets of weft yarns that are tied together to form a single fabric layer. The fabric is used as a reinforcement and is disposed along a peripheral surface of the belt including belt teeth as a wear-resistant fabric and a reinforcement member. The fabric also operates to help locate tensile members of the belt for controlling PLD.
U.S. Pat. No. 4,392,842 (Skura et al.) discloses a stretchable fabric reinforcement. The reinforcement is used in two layers of a toothed belt where one layer is disposed at a peripheral surface including the belt teeth and the other layer is embedded as a suspended layer in the belt teeth as a reinforcement.
U.S. Pat. No. 5,536,214 (Akita et al.) discloses a non-woven fabric where in the prefered form, it is needle punched which bonds discontinuous fibers of the fabric together by entangling some fibers. The non-woven fabric is used as an embedded reinforcement in a toothed belt body of cast urethane. The fabric is disposed in the belt body in a land area between belt teeth where it is compressed to help control PLD and in the belt teeth where it is expanded and serves as an embedded reinforcement for the belt teeth.